The new structure also includes the creation of a smaller board of directors and the adoption of a one-member one-vote system.

Ursula Lidbetter, Co-op chair, said: "These reforms represent the final crucial step in delivering the change necessary to return the group to health.

"This will strengthen the society and enable us to move forward with the urgent work to rebuild the business and deliver on our renewed purpose, in the interests of all our colleagues and our millions of members and customers."

A poll in May saw unanimous support for the key principles behind the reforms.

The changes, which followed a review by former City minister Lord Myners, required the backing of a two-thirds majoriy.

The board will consist of an independent chairman, five independent non-executive directors, two executive directors and three elected directors.

Last year saw the Co-op group experience its worst crisis in its 150-year history after it discovered a £1.5bn hole in its balance sheet.

A separate report by Sir Christopher Kelly found the group had let down its members by failing to provide "proper stewardship".

Its stake in the bank has now fallen from 100% to 20% after a rescue plan that saw bondholders, including US hedge funds, take majority ownership.

Last week, the lender reported first-half losses had shrunk from £845m to £76m.